mailey



Jan. 13, 1931.

R. DQMAILEY THERMOS TATICALLY CONTROLLED SWITCH Filed May 9, 1

/ H IS ATTO Patented Jan, 13 1931' warren STATES PATENT oi-"FicE ROY D. MAILEY, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO GENERAL ELECTRIC VAI'OR LAMP COMPANY, OF HOBOKEN, NEW JERSEY, A CORPORATION OF NEW JERSEY Application filed May 9,

My present invention relates to thermostatically controlled switches for electric circuits and more particularly to a thermostatic control ,device which is adapted to open and close such switches with abrupt and clear cut movement for the purpose of opening and closing said circuits with a minimum amount or no arcing at the switch.

It further relates to such thermostatic switch controlling apparatus for electric heaters such as used in fiat irons, ranges and the like.

In thermostats heretofore used for controlling electric circuits there has been slow and continuous movement that has in many cases resulted in the corroding of contacts through arcing therebetween, this lack of positive action rendering the device impractical for many uses. According to my invention, however, I provide a thermostat of such a nature and having such connection with the switch that changes in the thermostat due to changes in surrounding temperature will be accumulated over a period of time and range of temperature and will be releasable suddenly and at a predetermined temperature so thataccumulative forces resulting through such changes will act to positively open or close the switch with a sudden and rapid movement.

In the practical embodiment of my invention I provide a bimetallic thermostat element or elements formed into a flat spiral or spirals and connected to a switch in a manner hereinafter fully described so that at predetermined temperatures and. after predetermined movements of such thermostatic element the switch will be moved by spring compression produced in the element with a positive and abrupt action to the completion of the respective operations of the switch.

In the drawings forming part of this. application:

Fig. 1 is a plan view of the interior of an electric flat iron having incorporated therein a thermostat comprising an electric mercury switch in the circuit of the flat iron and operated by a pair of flat spiral bimetallic thermostat elements which are mounted to oppose each other in winding or THERMOSTATICALLY-CONTROLLED swrrcn 1925. Serial No. 29,026.

unwinding movements thereofand which carry between their respective outer ends the said mercury switch in such a manner that upon expansion and unwinding of the spiral elements the binding will be produced between said ends through the switch mounting until a given direction to the action of the forces which tend to move said ends is obtained whereupon the binding condition is passed out of and the spiral elements will unwind to a given degree with a quick and rapid movement which is utilized for the quick operation of the mercury switch. In the return or winding move ment of the element upon a consequent fall in temperature a similar binding period is passed through and abruptly left with a similar quick and rapidmovement of the mercury switch back into the original position, and

Fig. 2 is a sectional elevational view taken along the line 2-2 of Fig. 1,

Fig. 3 is an elevational view of a modified arrangement using a single bimetallic element, and

Fig. 4 is an elevational view, with a part cut away, of an arrangement somewhat similar tothat of Fig. 3.

In the drawings the base 1 of the flat iron carries in the groove 2 thereof the spiral heating element 3. On said base 1 is the plate 5 which carries the supporting standards 6 and 7 which are insulated by the members 8 and 9. At their upper ends said standards 6 and 7 support in a common vertical plane the flat spiral bimetallic thermostat elements 11 and 12 respectively which are shown as being both wound in the same direction but as having their ends extending in opposite directions. That is, each of the spirals is of the same number of turns as the other but one is mounted with a 180 rotation with respect to the other. The outer ends ofsaid elements 11 and 12 are pivotally connected together through link 14 which carries at one side thereof the mercury switch 15 which has its terminals connected to said thermostat elements 11 and 12 respectively through the pintle members 17 and 18 of said link 14, these being insulated from each other by the side members 19, 19 of the link 14 which are of insulating material. The thermostat element 11 through standard 6 connects through the lead 21 to one end of said heating element 3 and the other spiral member 12 connects through its standard 7 and the lead 22 to a suitable terminal for connection to a power main. The other end of said heating element 3 connects through the lead 23 to another terminal for connection with the other power main.

In the use and operation of the thermostat of my invention when the switch is in the closed position and heat is generated by the heating element of the iron the spiral bimetallic thermostat elements 11 and 12 from 'the nature and materials of their construction in a manner well known in the art tend to uncurl and straighten out. Their inner ends being fixed to the posts 6 and 7 a maximum force willbe exerted on their outer ends which are so connectedby the link 14 that the force tending to move them will up to a predetermined point oppose each other and bind the ends, so that the elements will not move at their outer ends but at points intermediate their respective ends whereby the forces are stored up in a spring tension efi'ect procured in the spiral elements. But while said outer ends are bound by the opposing forces there is a continued tendency for these elements to uncurl. There t en comes a time when the increase of the temperature to or past a predetermined point when this tendency to uncurl will produce forces having resultants which will move said outer ends of the spiral elements past the binding point and when this does happen it can be seen that due to the stored up forces in the thermostat elements acting as springsthis movement will be sudden. and rapid and will move the mercury switch to open it due to this sudden and ra id movement which is highly desirable in an electric switch as is well known in the art. As indicated in the dotted lines of Fig. 2 this movement will carry the outer ends of the thermostat elements to points where a curling of "the elements through the cooling thereof will produce a binding of said outer ends by said. link 14 which in this position is interposed between these ends in the direction of their movements or tendency to move caused by such curling. Again a point will be reached when the opposing forces will have resultants which will move said outer ends past the binding position and through the spring tension produced by the stored up forces in the spiral elements the mercury switch will again be moved with a sudden and rapid motion to close it.

My invention may be embodied in other forms without departing from the spirit thereof and it is not, therefore, limited .to the embodiment shown and described. ()ne alternative form, for instance, has a single spiral thermostat connected to one end of an element equivalent to the link 14 as shown in Figs. 3 or 4, the other end of which would have either "a fixed connection, as shown in Fig. 3, or a sliding connection as shown at 24 in Fig. 4.

I claim:

1. A thermostat comprising an electric switch and a pair of flat spiral bimetallic thermostat elements fixed at one end and connected at their other ends through a link and having an operative connection with an element of said switch through said link. first said connection being made in such a manner that upon tendency of movement of the elements through a change of temperature the elements will bind on said link and forces tending to further move it will be stored in flexing the elements against their tendency to stay in a natural position through a continued increase in temperature until such forces acquire a direction and magnitude which will move the element ends and the link past the binding position to a position in which they will again be bound upon a return movement due to an opposite change in temperature.

2. A thermostat comprising an electric switch and a pair of fiat spiral bimetallic thermostat elements fixed at one end and connected at their other ends through a link and having an operative connection with said switch through said link, first said connection being made in such a manner that upon tendency of movement of the elements through a change of temperature the elements will bind on said link and forces tending to further move it will be stored in flexing the elements against their tendency to stay in a natural position through a continued increase in'temperature until such forces acquire a direction and magnitude which will move the element ends and the link past the binding position to a position in which they will again be bound upon a return movement due to an opposite change in temperature.

3. A thermostat comprising an electric switch, a link, and a fiat spiral bimetallic thermostat element fixed at one end and connected at its other end to an element of said switch through said link, said link having substantially fixed pivotal point, the tendency of movement of said bimetallic element through a change of temperature being to- -ward said pivotal point, whereby the element will bind on said link and forces tending to further move it will be stored in flexing the element against its tendency to stay in a natural position through a continued increase in temperature until such forces acquire a direction and magnitude which will move the element end and the iii link past the binding position to a position I in which they will again be bound u on a return movement due to an opposite c ange in temperature.

4. A thermostat comprising an electric switch and a pair-of fiat spiral bimetallic thermostat elements fixed at one end and connected at their other ends having an operative connection with. said switch through a link, said connection being made in such a manner that upon tendency of movement of the elements through a change of temperature the elements will bind on said link and forces tending to further move it will be stored in flexing. the elements against their tendency to stay in a natural position through a continued increase in temperature-until such forces acquire a direction and magnitude which will move the element ends and the link past'the binding position to a position in which they w' again be bound upon a return movement due .to an opposite change in temperature said link having parts of insulating material and serving to electrically insulate the movin ends of said elements from each other, and said elements serving as leads from terminals of said switch. 7 V

5. A thermally operated switch comprising a link, a fluid switch operated by said link, and a flat spiral bimetallic element fixed at one end and connected at its other end to said link, said link being supported in such a manner that it tends to rotate about a substantially fixed point, the tendency of movement of the element through a change of temperature being in a direction which exerts pressure on said link toward said fixed point whereby the element will bind on said link, and forces tending to further move it will be stored in flexing the element against its tendency to stay in a natural position through a continued increase in temperature until such forces acquire a direction and magnitude which will move the element 'end and the link past the binding position to a position in which they will again be bound upon a return movement due to an opposite change in temperature. I

Signed at Hoboken in the county of Hudson and State of New Jersey this 8th day of May A. D. 1925.

- ROY D. MAILEY. 

